Organic materials, whether natural or synthetic, are conventionally protected against degradation by ultraviolet (UV) light by incorporating a UV light stabilizer in the material. Many classes of compounds are known to be useful UV light stabilizers, some being more effective than others. Particularly effective 2-keto-diazacycloalkanes which provide stabilized compositions resistant to degradation by UV light, include the 2-keto-1,4-diazacycloalkanes disclosed in U.S. Pat. No. 4,190,571; and, the 2-keto-1,5-diazacycloalkanes disclosed in U.S. Pat. No. 4,207,228. Other 2-keto-diazacycloalkanes useful as UV light stabilizers are disclosed in U.S. Pat. Nos. 3,919,234; 3,920,659; and 3,928,330 which teach substituted piperazinediones. Cycloalkanes useful as UV light stabilizers are disclosed in Ger. Offen. No. 2,315,042; Japanese Patents Nos. 7,453,571 and 7,453,572.
The compounds of this invention belong to a well-recognized chemical class of ultraviolet light stabilizers. They are multi-ringed triazine derivatives. Compounds of this class include piperidinyl-triazine derivatives such as are disclosed in U.S. Pat. No. 4,263,434 (hereafter "434" for brevity) and French Pat. No. 2181 059, each of which describe the preparation of monoaza ring substituents linked to a triazine ring, and teach the particular use of these derivatives as light stabilizers in polyolefins.
However, the compounds of the French patent are known to have poor resistance to extraction with an aqueous solvent which appears to be a characteristic of this class of compounds. The compounds of the '434 patent are known to have overcome, for the most part, such a disadvantage, presumably because of the particular linking of the piperidinyl substituents to the triazine ring. In addition to the different linking groups, compared with those of the French compounds, the '434 compounds include a single piperazine ring substituent, not part of a repeating unit, which is directly bonded to the triazine ring, that is, without any linking groups. Moreover, though substituted piperazinones are known to be effective stabilizers, there is no suggestion that linking such a piperazinone through at least a three-atom chain of one N (nitrogen) atom and at least two C (carbon) atoms to a triazine ring, might impart compositions containing such distally linked piperazinone substituents exceptional properties, including fastness to extraction with aqueous solutions.
The concept of structurally changing the nature of the linking group in multi-ringed triazine derivatives, and changing the structure of rings to which the triazine ring is linked, initiated the search for effective triazine-based compounds. The heretofore unknown effectiveness of (a) reductive alkylation of a branched chain polyalkylenepolyamine ("PAPA") with a ketone, and (b) the ketoform reaction to preferentially cyclize proximate primary and secondary amine groups in alkylated PAPA which contain a sterically tailored hindered primary amine group which is nevertheless reactive, permitted the implementation of the concept. Testing the compounds as stabilizers in various synthetic resins, and particularly in polyolefins, proved that a substituted piperazinone linked to a triazine ring through one N atom and at least two C atoms (hence "distally linked"), yields effective stabilizers.
The present invention is particularly directed to (a) novel alkylated PAPA, (b) a novel synthesis for the alkylated PAPA, (c) novel uv light stabilizers classed as hindered amine-triazines, more specifically 2-oxo-piperazinyl-triazine ("PIP-T") derivatives, (d) novel syntheses for the PIP-T derivatives, and (e) novel compositions in which 2-oxo-piperazinyl-triazine derivatives are incorporated. The novel PIP-T compounds have at least one substituted piperazinone substituent which is distally linked to a triazine ring, and when, in addition, a piperidinyl, piperazinyl or other substituent is directly linked to the triazine ring, the piperidinyl, piperazinyl or other substituent may become part of a repeating unit. It is to this difference in structure to which the effectiveness of these compounds is attributed.
The reductive alkylation of polyalkylenepolyamines ("PAPA") is well known and described with numerous examples in the chapter entitled "Preparation of Amines by Reductive Alkylation" by W. S. Emerson in Organic Reactions, Vol. 4, John Wiley & Sons, New York, N.Y. However there is no teaching that reductive alkylation may result in alkylation only at a particular primary amino group to the exclusion of all other amino groups, such result being obtained with a PAPA only by hindering one of the two primary amine groups and reacting with a ketone.
The synthesis of the novel stabilizers of this invention is facilitated by the peculiar action of certain onium salts in an aqueous alkaline medium, which action facilitates the interaction of an amine nycleophilic agent such as a primary or secondary amine, with chloroform or other trichloromethide generating agent, and a ketone or aromatic aldehyde. The organic onium salts of nitrogen, phosphorus and sulfur are well known. They are ionized in aqueous solutions to form stable cations. Certain onium salts have provided the basis for phase transfer catalysis in a wide variety of reactions, a recent and comprehensive review of which is contained in Angewandte Chemie, International Edition in English, 16 493-558 (August 1977). Discussed therein are various anion transfer reactions where the onium salt exchanges its original anion for other anions in the aqueous phase. These ion pairs can then enter a water immiscible, organic liquid phase, making it possible to carry out chemistry there with the transported anion, including OH.sup.- ions. Many reactions involving water immiscible solutions of various simple organic molecules have been described. Though the use of phase transfer catalysts facilitate the cyclization of an appropriately sterically hindered branched chain amine having proximate primary and secondary amine groups amongst plural amine groups in the chain, the reaction has also been found to proceed, though relatively slowly, by simply using a large excess of the ketone or aromatic aldehyde either of which is the essential carbonyl containing compound which contributes the carbonyl group to the 2-position of the diazacycloalkane ring.
A phase transfer catalyzed reaction known as the "ketoform reaction" is disclosed in U.S. Pat. No. 4,167,512, which proceeds by virtue of a phase transfer catalyzed reaction mechanism in which an amine, a haloform and a carbonyl containing ("carbonyl") compound are separate reactants. This reaction is illustrated in one particular example by the reaction of a N,N'-alkyl substituted ethylene diamine with acetone and chloroform; and, in another example, with o-phenylene diamine reacted with cyclohexanone and chloroform. The reaction product in each example is a 2-keto-1,4-diazacycloalkane.
Though both ketones and aldehydes are taught as being effective reactants in the ketoform reaction, it has now been discovered that only ketones are effective in the cyclization of a PAPA. Accordingly, our present invention extends the use of the ketoform reaction to novel alkylated PAPA.
A more detailed teaching of the ketoform synthesis will be found in an article titled "Hindered Amines. Novel Synthesis of 1,3,3,5,5-Pentasubstituted 2-Piperazinones" by John T. Lai in J. Org. Chem. 45, 754 (1980).